These are both from the list compiled in my Media 1 tute and from a reading in Cinema studies.

Volume – Loudness, amplitude, breadth. Contrasting volume such as silence with loudness makes a dramatic statement. ie. A gunshot ringing through a silent night.
Music – A great use of music is on Hack for example. As a conversation gains traction they often use a simple drum beat to create rhythm in the convo.
Narration – Have a clear difference between the voice leading the conversation and those contributing or being interviewed. Maybe use a different mic, a different vocal tone and non-diegetic sound to bring us back to “the room”
SFX  – Use these to make your recording visual. Generate an atmosphere around the person you interview, the topic you’re talking to.
Interviews – sometime’s it’s helpful to lessen the quality of the interview, including some background noise to show it’s a contributor.
Conversations – two or more people on the panel are having a casual and converse interaction. Differentiate their voices and avoid overlapping speech unless that is a desired effect.
Archival recordings – for sfx you can’t record yourself. or perhaps iconic podcast/radio noises.
Vox Pop – voice recordings of public answering the same question.
Phonecalls – get your interviewee on the phone if you can’t get them in public.

Begin with a question: Why do we sleep? Are we an audience? Do audiences still exist? the passive kind etc. idk I will update with a question soon.